Thanks to those who helped me understand flash in a previous thread. I've been leaning toward the 430ex as a sort of "starter" flash on my Rebel T2i. When I went to the camera store, the 430 comes with a $100 rebate that drops the price to around $230. But then they showed me a used 420 for $129. The 430 of course has a few more bells and whisles, but is it worth the extra $100? I've never used flash very much, but am learning macro for which a flash would be useful. And I could probably invent some more uses for it.
I anticipate upgrading the camera in a few years if that makes a difference.
I can't speak for your budget, but when you get into "flash", you quickly learn that the best light is created by getting the flash OFF the camera and also diffusing it so that it comes from a large broad source (not a pin-point source). This is because on-camera flash doesn't create much (if any) shadow and that makes subjects look "flat" (2-dimensional). "Good light" requires "good shadows" (ironically the quality of the "light" is actually more about the quality of the "shadows" and not the "light"). When you get the flash off the camera, you can light from a source coming from one side -- creating some shadows (that you control based on placement of the light). That creates the dimensionality to your subjects.
In other words... if it's worth investing in a flash, then it's probably a good idea to invest in a flash that can be used "off camera".
There is a problem since you have a T2i. Canon didn't add the ability of the on-camera flash to act as a remote trigger until the T3i (mid-level and above cameras such as the 60D and 7D had it and then they added it to the T3i (that was the first "Rebel" model to get the feature.) Since the introduction of the T3i, I think each new EOS camera (at least every model that includes a built-in flash) supports the ability to be a "master" and trigger and off-camera "slave".)
But this means that for you, having a T2i, would require a trigger if you want to use the flash off-camera. Most inexpesive triggers are "manual" flash only (meaning you manually set the amount of power to use when the flash is triggered -- it's not E-TTL where the computer figures out how much power is needed.) Canon's ST-E2 on-camera trigger can trigger an off-camera slave in "optical" mode. the ST-E3-RT can trigger an off-camera slave in "radio" mode but this only works with Canon speedlites that support "radio" mode (those models have an "RT" suffix in the name.)
Canon updated the 430EX II and it's now the 430EX III-RT. The new feature is the "RT" which indicates that it can be radio-triggered (the previous units could only be "optically" triggered and that meant they required a "line of sight" from the trigger flash to the remote flash.)
I had a 430EX II and it was a very solid workhorse flash (very reliable). I've since donated mine to a friend (I now use 600EX-RT units.)
I LOVE the radio. Rock-solid reliability -- the flashes fire every time.
Thanks, Tim, this is good food for thought. I knew that getting the flash off the camera gives much better results, and that the 430ex I was looking at does not have the RT feature (a moot point, really, given my camera). The guy at the store said something about a cable so I could use it off-camera, but I'm not sure now which flash he was talking about. The 430 has a little built-in diffuser (it slides out of a slot on top).
Back to the store, I think, to see how the thing will work with my camera. As an aside, I would never go to my local store and pick their brains and try out their gear, only to go buy it online.